The invention relates to a combination of a ski binding, particularly a cross-country, touring or telemark binding and of a boot adapted thereto, the forward end of which is held in the binding by a resiliently biased clamping element in such a way that the heel of the shoe can be freely raised when used in touring, cross-country skiing or the like use.
Such combinations of a ski binding and of a boot adapted thereto are generally known; in the known solutions a clamp cable is passed around the boot heel as a retaining member. Such a construction is for example described in FR-A 756 374 or CH-A-194 783. For a corresponding construction of a touring ski binding, reference is made to DE-C 35 39 315. All these known combinations are relatively bulky in construction. A disadvantage is also that lifting of the boot heel during touring, cross-country skiing or downhill skiing in the telemark style is in fact prevented by the clamp cable passed around the boot heel. In addition, when the clamp cable is arranged around the boot heel the said heel can be moved laterally, so that exact lateral guidance of the ski is not possible. The transfer of power to the ski is likewise impaired. Finally, a considerable disadvantage is that the position of the bending line of the sole extending transversely to the longitudinal direction of the boot or sole is not defined. It migrates within a relatively large area, i.e. is displaced upon each lift of the boot heel. Consequently, the sole and boot deformation forces alter in a corresponding way. The cross-country skier is subjected to varying degrees of stress upon each lift of the boot heel.
There is known from DE-OS 41 03 068 a ski cross-country binding in which a clamp cable which can be passed around the boot heel fixes the ski boot to the cover surface of a ski-mounted toe iron by means of a clamp cable coupled to a tightening mechanism. In this case the clamp cable has a device for altering its effective length, and a part of the clamp cable is replaced by a traction spring. At the portion of the clamp cable which can be passed around the boot heel, a clamp lever which can be supported on the boot sole is mounted to pivot about a pivotal axis located parallel to the clamp cable. In this binding also, the above mentioned problems arise, due to the varying sole and boot deformation forces.
There is known from DE-GM 16 96 548 a ski binding with a tightening strap engaging on the forward end of a ski boot, the tightener mounted in front of the ski boot on the ski cover surface being engaged in a metal tab secured to the forward sole of the ski boot and drawing it between retaining jaws. This engagement binding is intended to ensure that it releases automatically during disconnections, as soon as the rear portion of the ski boot is raised to an unusual height from the ski cover surface. Such a ski binding enables only imprecise guidance of the ski and power transmission to the ski and is unsuitable both for cross-country skiing or for downhill skiing in the telemark style.
The object underlying the present invention is to improve the already mentioned combination of a ski binding and of a boot adapted thereto in that the boot heel can be raised substantially unhindered and to a great extent, and that a defined deformation of the boot or of the sole of the same is ensured, so that the ski guidance and power transmission to the ski are not impaired thereby and the maximum proportion of the energy applied by the skier can be converted into speed and ski guidance. In addition, the construction according to the invention is to be characterised by a compact structure.
This object is achieved in that the clamp member engages on the forward sole of the shoe, particularly between the area of the ball of the foot and the rear end.
According to a basic idea of the invention the clamp member is formed on a clamp cable which is passed around at least a portion of the forward sole. The clamp cable construction is reduced to a minimum without impairing the power transmission to the ski or the ski guidance. On the contrary, the binding of the boot both at the front end of the same and also at the forward sole between the ball area and the rear end of the same affords the skier a reliably functioning connection with the ski with, in comparison to prior art, considerably increased mobility of the boot heel. The double binding of the boot according to the invention leads to a greater degree of efficiency as regards power transmission. The ski guidance is also ensured by the coupling both at the forward end of the boot and also between the ball and the instep area of the forward sole. Accordingly the combination according to the invention is also quite specially suitable for the telemark style. According to another basic idea of the invention the clamp member is designed as a resilient elastic part in the plane defined by the raising of the boot heel, which is attached at the forward end of the ski to the ski itself or at the binding, while the rear-of-ski end may be coupled to the boot, particularly to its sole.
This construction with a resilient elastic portion or flexible retaining member permits a defined and substantially unhindered raising of the boot heel, precise ski guidance being ensured at any elevated position of the boot heel, in that the retaining member is resiliently elastic only in a longitudinal plane vertical to the ski cover surface. This also ensures that no force is lost through return of the rear end of the boot, moved towards the side, into a position parallel to the longitudinal direction of the ski, as is the case in previous cable bindings. The degree of efficiency with respect to power transmission is in this construction of the retaining member accordingly higher than in prior art. The combination according to the invention is thus suitable not only for cross-country skiing, but due to its good lateral guidance and improved power transmission, is particularly suitable for ski touring and downhill skiing, particularly in the telemark style.
The results of the flexible retaining member is that no large-dimension retaining jaws are required for the forward end of the boot for lateral stability. Thus the forward sole area can be just as soft as in a previous walking boot, as the boot is held both at its forward end by a retaining part on the binding, and also in the centre of the boot or in the ball area on the retaining member.
Finally, in the construction according to the invention the bending line of the sole is substantially defined, as it is determined by the bending line of the resilient elastic retaining member.
In all, by means of the invention a maximum proportion of the energy applied by the skier can be converted into ski guidance and/or speed.
Preferred constructive details and embodiments of the binding-boot combination according to the invention are described in the secondary claims, in which respect the sole measures according to claims 9 to 12 should be emphasised, by means of which a particularly resilient elastic rubber sole can be stabilised. Above all, the measures named there give rise to lateral stability and distortion resistance of the sole, so that the flexibility in the longitudinal direction of the boot is not impaired. Particular reference is also made to the measures according to claims 15 to 18, which permit a simple alteration in the bending line of the boot sole as required, particularly of the boot forward sole.